JPH0727960A - Plastic lens barrel - Google Patents

Abstract

PURPOSE:To prevent an excess light beam from being reflected toward the exiting side of a lens barrel and to prevent the occurrence of ghost and flare. CONSTITUTION:A light shading thread 2 of waveform is provided on the inner peripheral surface of the lens barrel 1. The thread 2 is formed so that the height of the vertex part 3 thereof may be higher as it goes from the incident side to the exiting side of a light beam. The excess light beam cast on the side surface part of the thread 2 is reflected toward the incident side. The execess light beam cast on the vertex part 3 is reflected toward the exiting side, but it casts on the adjacent high side surface part of the thread 2 and is reflected toward the incident side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic lens barrel for mounting an optical member, and more particularly to a plastic lens barrel having means for preventing internal reflection of surplus light rays.

[0002]

2. Description of the Related Art Conventionally, in an optical device such as a camera, a frame for mounting an optical member and a lens barrel have a light-shielding line, an antireflection coating, a satin finish, etc. to prevent ghost and flare due to internal reflection. It has been subjected.

Further, Japanese Patent Publication No. 62-11905 discloses a technique for absorbing surplus light rays by implanting fiber piles on the surface of a base adhered to the inside of a camera frame, a lens barrel or the like via an adhesive. Is disclosed, specifically, the fiber pile protruding from the surface of the base is made black and its cross section is formed into an elliptical or gourd shape to enhance the light absorption by repeating the bending diffraction of the surplus light, In addition, the surface of the adhesive layer and the surface of the fiber pile are coated with a flexible synthetic resin to prevent the fiber pile from falling off.

Further, Japanese Patent Laid-Open No. 3-271708 discloses a technique for preventing internal reflection by forming a portion other than a necessary portion for holding an optical member in a lens barrel by thinning it out. .

[0005]

However, the above-mentioned conventional technique has the following problems. (1) When the light-shielding line is provided, when the material of the frame and the lens barrel is metal, secondary processing such as cutting is required, which increases the cost of the product. Further, in the case of plastic, the filling rate of the plastic at the tip of the light-shielding line becomes poor and the tip is rounded, and the light ray hitting that portion is reflected on the film surface to cause ghost flare. (2) When the antireflection coating is applied, the cost of the product increases because the number of coating steps increases. (3) When the satin finish is applied and the inner walls of the frame and the lens barrel are close to the optical path, the effect of reducing the reflection due to the satin finish becomes low, and ghost flare cannot be prevented. (4) In the case of Japanese Examined Patent Publication No. 62-11905, while the fiber pile is planted on the base through an adhesive, each fiber pulse and the adhesive layer are coated with a synthetic resin.
The manufacturing process is complicated and the product cost is high. (5) In the case of Japanese Patent Laid-Open No. 3-271708, since the meat is removed, the strength becomes weak.

The present invention has been made in view of the above-mentioned problems of the prior art, does not require secondary processing after molding such as cutting and coating, is inexpensive in cost, has a high reflection efficiency of surplus rays, and has a high strength. An object of the present invention is to provide a plastic lens barrel having a strong internal reflection preventing mechanism.

[0007]

In order to achieve the above object, the present invention is constructed as shown in the conceptual diagrams of FIGS. 1 to 4. FIG. 1 is an overall view of an optical system in a plastic lens barrel 1, which includes three first-group lenses A and three second-group lenses B.
Is mounted on the same plastic lens barrel 1, and a light-shielding line 2 is provided on the inner wall of the plastic lens barrel 1 between the first lens group A and the second lens group B.

As shown in FIGS. 2 and 3, the light-shielding line 2 has a corrugated cross-sectional shape, and one of the light-shielding lines 1 is formed.
The corrugated top portion 3 forming one book is formed so as to gradually increase from the light incident side to the light emitting side. Further, as shown in FIG. 4, the light-shielding line 2 may be formed by applying satin treatment to the entire light-shielding line 2 so that the height of the corrugated crown 3 is the same.

[0009]

According to the above construction, most of the surplus light rays C which hit the light shielding line 2 hit the side surface portion 4 of the light shielding line 2 and are reflected to the incident side. Further, the surplus light ray C hitting the crown 3 of the light-shielding line 2 is reflected toward the exit side because the crown 3 is rounded, but the height of the crown 3 is formed higher toward the exit side. As shown in FIGS. 2 and 3, the surplus light ray C reflected to the exit side hits the adjacent side surface portion 4 and is reflected to the entrance side. Further, when the entire shading line 2 is subjected to the satin finish, the surplus light ray C that hits the crown 3 of the shading line 2 is diffusely reflected and diffused. As described above, it is possible to reduce the reflection of the surplus light ray C on the exit side in the lens barrel 1.

[0010]

First Embodiment FIG. 5 is a sectional view showing a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing a light shielding line. 1 in FIG.
Is a lens barrel, and includes a fixed barrel 11 and a relay barrel 12 slidably provided in an inner diameter portion of the fixed barrel 11. The fixed barrel 11 and the relay barrel 12 are made of a plastic molded product. Has been formed. The first lens group 13 is fixed to the fixed lens barrel 11, and the second lens group 14 and the third lens group 15 are fixed to the relay lens barrel 12 with a required gap. A light-shielding line 16 is provided on the inner peripheral wall of the relay lens barrel 12 at the above-mentioned interval.
Are formed when the relay barrel 12 is molded.

As shown in FIG. 6, the light-shielding line 16 has a corrugated cross-section, and the crown 17 of each corrugation is formed from the incident side (the side of the first lens group 13 of the lens) toward the emitting side thereof. The height is increased by 0.1 mm. The waveform is formed so as to increase toward the exit side, and the light-shielding line 16 on the most incident side (the second lens group side 14)
Has a line width of 0.3 mm and an angle between the crown 17 and the valley 18 of 90 °.

In the above structure, the light rays that have entered the fixed lens barrel 11 and the relay lens barrel 12 from the incident side are in the first group 1 of the lens.
After passing through the third and second lens groups 14, the surplus light ray C strikes the inner peripheral wall of the relay barrel 12 between the second lens group 14 and the third lens group 15. At this time, most of the surplus rays C are the light-shielding lines 1.
The light beam strikes the side surface portion 19 of 6 and is reflected to the incident side. on the other hand,
Excess light ray C that hits the crown 17 of the light-shielding line 16 (waveform)
Is reflected on the emission side because the top 17 is rounded due to defective resin filling during molding of the relay barrel 12, but the height of the light-shielding line 16 increases toward the emission side. The surplus light ray C reflected on the emission side also strikes the side surface portion 19 of the adjacent light shielding line 16 and is reflected on the incidence side.

According to this embodiment, the side surface portion 1 of the light shielding line 16 is
9 and since the surplus light ray C which hits the crown 17 can be reflected to the incident side, the occurrence of ghost flare is extremely reduced.

[0014]

[Embodiment 2] FIG. 7 is an enlarged sectional view showing a light-shielding line 20 according to Embodiment 2 of the present invention. The light-shielding line 20 is formed in the same shape for each of the corrugated lines, and is 1/10 so that the top 21 and the valley 22 of the corrugation become higher from the incident side to the emitting side. Is formed with a gradient S of. That is, the relay barrel 12 is formed such that the inner peripheral surface between the second lens group 14 and the third lens group 15 (see FIG. 5) of the lens has the above-described gradient S from the incident side toward the emission side. The light shielding line 20 having the same shape is provided on the peripheral surface.

In the above structure, as in the first embodiment, most of the surplus light rays strike the side surface portion 23 of the light shielding line 20 and are reflected to the incident side, and the crown portion 2 of the light shielding line 20.
Since 1 increases from the incident side to the exit side, the surplus light ray that hits the crown 21 of the light-shielding line 20 and is reflected on the light-emitting side also strikes the side surface portion 23 to the adjacent light-shielding line 20 and is reflected on the incident side. . According to the present embodiment, it is possible to reduce ghost flare as in the first embodiment.

[0016]

Third Embodiment FIG. 8 is a sectional view showing a third embodiment of the present invention, and FIG. 9 is an enlarged sectional view showing a light shielding line. In this embodiment, the light-shielding line 31 is formed by performing satin finish on the whole. In the light-shielding line 31, the heights of the individual crowns 32 are all equal, the line width is 0.3 mm, and the angle between the crown 32 and the valley 33 is 90 °. Other configurations of the lens barrel 30 are similar to those of the first embodiment.

The basic operation of this embodiment is the same as that of the first and second embodiments, but the surplus light ray C which hits the crown 32 of the light-shielding line 31 is diffused by the fine unevenness due to the satin finish, and is emitted. The reflection of the surplus light ray C to is extremely reduced. According to the present embodiment, the ghost
Flare can be reduced.

[0018]

As described above, according to the present invention, since the light-shielding line can be formed at the time of molding the lens barrel, the secondary processing is not required after the lens barrel is molded, so that it can be obtained easily and inexpensively. Strengthening is strengthened because meat is not removed. Furthermore, since the shading line is formed so that the top of the head becomes higher from the entrance side to the exit side, or the entire shading line part is formed in a satin finish, the reflection efficiency of the surplus light inside the lens barrel to the entrance side is improved. Therefore, the occurrence of ghost flare can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view conceptually showing the present invention.

FIG. 2 is an enlarged sectional view showing a light shielding line of the present invention.

FIG. 3 is an enlarged sectional view showing a light shielding line of the present invention.

FIG. 4 is an enlarged sectional view showing a light shielding line of the present invention.

FIG. 5 is a cross-sectional view showing a first embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view showing a light-shielding line according to the first embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view showing a light shielding line according to the second embodiment of the present invention.

FIG. 8 is a sectional view showing a third embodiment of the present invention.

FIG. 9 is an enlarged cross-sectional view showing a light shielding line according to a third embodiment of the present invention.

[Explanation of symbols]

 1,10,30 Plastic lens barrel 2,16,20,31 Light-shielding line 3,17,21,32 Crown C Extra light

Claims (2)

[Claims] 1. A lens barrel made of plastic having a light-shielding line on its inner surface, wherein the light-shielding line is formed in a corrugated shape, and the top of the light-shielding line becomes higher from the incident side of a light ray to the emitting side thereof. A plastic lens barrel characterized by being formed as described above. 2. A lens barrel made of plastic having an inner surface with a light-shielding line, wherein the light-shielding line is formed in a corrugated shape, and the entire light-shielding line portion is subjected to a satin finish. Cylinder.